The invention relates to a deadbolt assembly having two selectable backset distances which permit a cylinder lock to be mounted on a door at one of two different distances from the edge of the door, and particularly to a dual backset deadbolt assembly which includes a deadbolt operating mechanism to cooperate with a cylinder lock having two deadbolt operating crank members capable of actuating a deadbolt to move in either one of two opposite directions, wherein the mechanism has two independently movable transmission units which can be selected to cooperate with one of the deadbolt operating crank members of the cylinder lock.
Deadbolt assemblies having two selectable backset distances are known in the art. U.S. Pat. No. 4,711,477, issued on an application of one of the present inventors, discloses a dual backset deadbolt assembly to cooperate with a cylinder lock which has a single rearwardly extending elongated crank member with an arched cross section for operating the deadbolt assembly. The deadbolt assembly comprises two side plates which are provided with two crank holes at two selectable backset distances for positioning the crank member. In this deadbolt assembly, the single crank member of the cylinder lock can actuate the deadbolt to move in a single direction. Generally, doors can be installed in two different manners, one manner being where the door can be opened by being moved towards the right and the other manner being where the door can be opened by being moved towards the left. For the door of the former case, the deadbolt should be able to retract to the right and be attached to the left side of the door. For the door of the latter case, the deadbolt must retract to the left and be attached to the right side of the door. A disadvantage of the single deadbolt operating crank member and the deadbolt assembly disclosed in the above mentioned patent is that the prior art crank member and deadbolt assembly cannot be used for both left opening and right opening door designs, as mentioned above and is applicable only for a door that can be opened in one direction either left or right.